stony-hearted 
adjective
Very cruel or unfeeling: Boris was a stony-hearted professional terrorist they are stony-hearted...
- Even stone-hearted Higgenbotham had a hard time keeping a dry eye.
- The TV finally arrived and you would have had to be a very stony-hearted New Zealander not to be moved by Maori Television Service's first day.
- Yes, many people like the book, and it would be stony-hearted of me not to be pleased at their pleasure.
- full (or tight) as a tick
- full out
- full page
- full pay
- full point
- full price
- full professor
- full professorship
- full ride
- full-rigged
- full-scale
- full score
- full-service broker
- full-service brokerage
- full sister
- full-size
- full-sized
- full steam (or speed) ahead
- full stop
- full term
- full-throated
- full-time
- full time
- full-timer
- full-toned